Strength Endurance Performance Research Articles

Effects of an eight-week bosu ball exercise program on core strength endurance and balance performance in intellectually disabled adolescents

Effects of an eight-week bosu ball exercise program on core strength endurance and balance performance in intellectually disabled adolescents

Enhancing GFRP fatigue durability for chassis component applications through glass fiber coupling variation

As the landscape of mobility trends continues to evolve, concerted efforts have been made to incorporate Carbon Fiber Reinforced Plastic (CFRP) into automotive components. However, the substantial increase in cost relative to the achieved weight reduction has limited its widespread adoption. Consequently, research endeavors have focused on exploring alternative composite materials, adapting fibers such as glass fibers, natural fibers, and recycled fibers, to reduce the cost of composite components. Of particular interest in the automotive industry is the utilization of Glass Fiber Reinforced Plastic (GFRP) in chassis components like leaf springs. Nevertheless, the development of GFRP leaf springs encounters a significant challenge related to the adhesive strength at the interface between epoxy resin and glass fibers, which is crucial for enhancing fatigue durability. While glass fibers were traditionally paired with unsaturated polyester or vinyl ester matrices, the pursuit of improved durability has led to the adoption of epoxy matrices. Regrettably, this transition has not consistently yielded the expected gains in interfacial adhesion.In light of these challenges, this study systematically compares the interfacial adhesion strength and fatigue endurance performance. For comparison, two coupling agents widely used commercially, amino silane and epoxy silane, were selected. Glass fibers treated with each coupling agent were purchased commercially, and glass fiber-reinforced plastic (GFRP) specimens were fabricated using the HP-RTM (High-Pressure Resin Transfer Molding) method. Static property evaluations and fatigue durability assessments were conducted using the fabricated specimens. The results showed that when epoxy silane was used as the coupling agent, the interlaminar shear strength (ILSS) increased by approximately 7 %. Furthermore, SEM(Scanning Electron Microscopes) analysis confirmed a significant enhancement in interfacial adhesion, providing support for the ILSS evaluation results. Consequently, the fatigue durability performance improved by approximately six-fold. This confirms that the improvement in interfacial adhesion due to the change in coupling agents led to enhanced fatigue durability performance.

SNP Diagnosis in Elite Athletes by Korean Athletic Performance

PURPOSE: The purpose of this study is to analyze SNPs related to performance (maximal strength vs. cardiovascular endurance) of world-class Korean elite athletes using the Genome-Wide Human SNP Array 6.0 and to determine genotypes related to maximal strength and cardiovascular endurance performance that are unique to “Koreans”.METHODS: Using the Genome-Wide Human SNP Array 6.0, we analyzed SNPs obtained from 54 world-class Korean elite athletes (Olympic participants/World Championship medalists). The group was divided into the 16 maximal strength group (12 males and 4 females weightlifters who had won medals at the Olympic and World Championships), 12 cardiovascular endurance group (12 males marathon runners who had run within 2 hours and 12 minutes in international competitions), and 26 individuals from the general population (25 males and 1 female). All the obtained SNPs were subjected to quality control (QC), and a total of 867,982 SNPs were analyzed between the marathon runners and general population subjects (641,040 SNPs) and between weightlifters and general population subjects (634,418 SNPs).RESULTS: The number of SNPs with more than two SNPs within 100 kb, which satisfied the threshold of sample QC and significance level of <i>p</i><.0001, was 60 in marathoners and 18 in weightlifters compared to the general population subjects. When the genomic features of SNPs of each performance trait were analyzed, the 60 SNPs for cardiovascular endurance with two or more SNPs within 100 kb that met the <i>p</i><.0001 threshold for significance were distributed across 15 regions, and the 18 SNPs for maximal strength were distributed across 7 regions.CONCLUSIONS: In conclusion, SNPs related to cardiovascular endurance and maximal strength suggest the possibility of producing gene chips to derive genotypes unique to “Koreans” in the future. Additionally, this study provides important basic data for further research.

The placebo effect of a pink non-caloric, artificially sweetened solution on strength endurance performance and psychological responses in trained individuals.

Background: The pink color enhances the perceived sweetness, increasing the individuals' expectation of the presence of sugar/carbohydrate in a beverage. Hence, it is plausible to speculate that providing a pink solution during exercise could induce an ergogenic benefit through a potential placebo effect. Aim: We examined whether ingesting a pink non-caloric, artificially sweetened solution can improve endurance strength exercise performance and psychological responses. Methods: Eighteen strength-trained individuals (34 ± 7 y; 1.74 ± 0.06 m; 79.86 ± 10.91 kg) completed three experimental trials in a randomized, single-blind, crossover counterbalanced fashion. In each trial, participants performed a 5-set strength endurance test at 70% of the one-repetition maximum in the bench press exercise, interspersed by 2 min. Before each set, participants ingested either a pink (PINK) or a transparent (TRANSP) non-caloric, artificially sweetened solution. A session without ingestion (CON) was also completed. Total number of repetitions and psychological responses such as motivation, emotional arousal, affect, and ratings of perceived exertion were obtained throughout the exercise protocol. Results: Total repetitions improved in PINK (60 ± 12 reps) compared to TRANSP (p = 0.03; 56 ± 10 reps; ES = 0.22; ±3.8%) and CON (p = 0.01; 56 ± 9 reps; ES = 0.33; ±6.6%), but no difference occurred between TRANSP and CON (p = 0.84; ES = 0.12; ±2.4%). Comparable responses were observed in motivation, emotional arousal, affect, and ratings of perceived exertion in PINK, TRANSP, and CON trials (all, p > 0.05), despite the greater total physical work performed in PINK trial. Conclusion: Ingesting a pink non-caloric, artificially sweetened solution improved strength endurance performance with comparable psychological responses. These results have implications for future nutritional studies and performance assessments in real-world sports scenarios.

The effects of ischemia during rest intervals on strength endurance performance.

The study aimed to evaluate the effects of ischemia used during the rest periods between successive sets on maximal number of performed repetitions, time under tension and bar velocity during the bench press exercise. Thirteen healthy resistance trained men volunteered for the study (age = 28.5 ± 7.1 years; body mass = 87.2 ± 8.6 kg; bench press 1RM = 143.1 ± 20.7 kg; training experience = 11.0 ± 6.9 years). In experimental protocol the subjects performed 5 sets of bench press exercise at 70%1RM with maximal number of repetitions in each and with 5 minutes rest periods between each set. During the ischemia condition occlusion with 80% arterial occlusion pressure (AOP) was applied using a 10 cm wide cuff, before the first set of the bench press exercise and during all rest periods between sets (for 4.5 minute). During the control condition no ischemia was applied. The two-way repeated measures ANOVA showed a statistically significant interaction effect for time under tension (p = 0.022; η2 = 0.20). However, the results did not show a statistically significant interaction effect for peak bar velocity (p = 0.28; η2 = 0.10) mean bar velocity (p = 0.38; η2 = 0.08), and for number of performed repetitions (p = 0.28; η2 = 0.09). The post hoc analysis for interaction showed significantly shorter time under tension for ischemia condition compared to control in set 1 (p < 0.01). The post hoc analysis for main effect of condition revealed that time under tension was significantly shorter for ischemia compared to control condition (p = 0.04). The results of this study indicate that ischemia intra-conditioning does not increase strength-endurance performance as well as bar velocity during bench press exercise performed to muscle failure.

Effects of Mental Fatigue on Strength Endurance: A Systematic Review and Meta-Analysis.

The purpose of the present systematic review and meta-analysis was to explore the effects of mental fatigue on upper and lower body strength endurance. Searches for studies were performed in the PubMed/MEDLINE and Web of Science databases. We included studies that compared the effects of a demanding cognitive task (set to induce mental fatigue) with a control condition on strength endurance in dynamic resistance exercise (i.e.,expressed as the number of performed repetitions at a given load). The data reported in the included studies were pooled in a random-effects meta-analysis of standardized mean differences. Seven studies were included in the review. We found that mental fatigue significantly reduced the number of performed repetitions for upper body exercises (standardized mean difference: -0.41; 95% confidence interval [-0.70, -0.12]; p = .006; I2 = 0%). Mental fatigue also significantly reduced the number of performed repetitions in the analysis for lower body exercises (standardized mean difference: -0.39; 95% confidence interval [-0.75, -0.04]; p = .03; I2 = 0%). Our results showed that performing a demanding cognitive task-which induces mental fatigue-impairs strength endurance performance. Collectively, our findings suggest that exposure to cognitive tasks that may induce mental fatigue should be minimized before strength endurance-based resistance exercise sessions.

Correlations between core muscle strength endurance and upper-extremity performance in adolescent male sub-elite handball players.

Handball is an Olympic contact sport with high physical, tactical, and technical demands by the players. Out of the different techniques, throwing is the most important one to be able to score. The objective of the study was to investigate the relationships between core muscle strength endurance (Bourban test: ventral, dorsal and lateral chain) and shoulder mobility/stability (Upper Quarter Y Balance test [YBT-UQ]) as well as throwing velocity in adolescent male sub-elite handball players (N = 32, age: 17.1 ± 0.7 years, height: 181.8 ± 6.3 cm, BMI: 24.6 ± 4.9 kg/m2). All participants were free of injuries at least two weeks prior to the study, experienced (training experience: 8.5 ± 3.3 years) handball players who were tested mid-season in the evening of one of their training sessions. Pearson correlations were calculated for core muscle strength endurance with (a) shoulder mobility/stability and (b) throwing velocity. The throwing arm reach displayed significant correlations (both p < 0.05) between the Bourban test (ventral chain) and the inferolateral reach direction (IL) of the YBT-UQ (r = 0.41) as well as the composite score (CS) (r = 0.34). For the dorsal chain, significant correlations (all p < 0.01) were found for the medial (MD) (r = 0.42) and IL (r = 0.61) reach direction as well as the CS (r = 0.51). For the right but not the left side of the lateral chain, significant correlations (both p < 0.05) were detected for the IL reach direction (r = 0.40) and the CS (r = 0.35). For the non-throwing arm reach, significant correlations were found between the ventral chain and the MD reach direction (r = 0.53, p < 0.01) as well as the CS (r = 0.31, p < 0.05). For the dorsal chain, significant correlations (all p < 0.01) were found for the MD (r = 0.47) and IL (r = 0.44) reach direction as well as the CS (r = 0.41). For the lateral chain, significant correlations were detected for the MD (left and right side: r = 0.49, p < 0.01) and IL (left and right side: r = 0.35, p < 0.05) reach direction as well as the CS (left and right side: r = 0.37, p < 0.05). The dorsal chain but not the ventral and lateral chain of the Bourban test showed a significant correlation with throwing velocity (r = 0.33, p < 0.05). Our results indicate that better core muscle strength endurance is associated with better shoulder mobility/stability as well as partially higher throwing velocity of adolescent male sub-elite handball players. Therefore, practitioners should integrate core muscle strength endurance exercises into the training routines to improve upper-extremity performance of this target group.

The Role of Velocity-Based Training (VBT) in Enhancing Athletic Performance in Trained Individuals: A Meta-Analysis of Controlled Trials.

Velocity-based training (VBT) is a rising auto-regulation method that dynamically regulates training loads to promote resistance training. However, the role of VBT in improving various athletic performances is still unclear. Hence, the presented study aimed to examine the role of VBT in improving lower limbs’ maximum strength, strength endurance, jump, and sprint performance among trained individuals. A systematic literature search was performed to identify studies on VBT for lower limb strength training via databases, including PubMed, Web of Science, Embase, EBSCO, Cochrane, CNKI (in Chinese), and Wanfang Database (in Chinese). Controlled trials that deployed VBT only without extra training content were considered. Eventually, nine studies with a total of 253 trained males (at least one year of training experience) were included in the meta-analysis. The pooled results suggest that VBT may effectively enhance lower limbs’ maximum strength (SMD = 0.76; p < 0.001; I2 = 0%), strength endurance (SMD = 1.19; p < 0.001; I2 = 2%), countermovement jump (SMD = 0.53; p < 0.001; I2 = 0%), and sprint ability (SMD of sprint time = −0.40; p < 0.001; I2 = 0%). These findings indicate the positive role of VBT in serving athletic training. Future research is warranted to focus on the effect of velocity loss of VBT on athletic performance.

Isolated Soy Protein Supplementation Combined With Resistance Training Improves Muscle Strength, Mass, and Physical Performance of Aging Female Mice.

Background/Purpose: In recent years, the aging population has gradually increased, and the aging process is accompanied by health-associated problems, such as loss of muscle mass and weakness. Therefore, it is important to explore alternative strategies for improving the health status and physical fitness of the aged population. In this study, we investigated the effect of soy protein supplementation combined with resistance training on changes in the muscle mass, muscle strength, and functional activity performance of aging mice. Methods: Female Institute of Cancer Research (ICR) mice were divided into four groups (n = 8 per group): sedentary control (SC), isolated soy protein (ISP) supplementation, resistance training (RT), and a combination of ISP and RT (ISP + RT). The mice in designated groups received oral ISP supplementation (0.123 g/kg/day), RT (5 days/week for a period of 4 weeks), or a combination of both ISP plus RT for 4 weeks. Afterward, we assessed muscle strength, endurance, and anaerobic endurance performance and analyzed blood biochemical and pathological tissue sections to investigate whether there were adverse effects or not in mice. Results: ISP supplementation effectively improved the muscle mass, muscle endurance, and endurance performance of aging female mice. The RT group not only showed similar results with ISP but also increased muscle strength and glycogen content. Nevertheless, the combination of ISP supplementation and RT had greater beneficial effects on muscle strength, physical performance, and glycogen levels (p < 0.05). In addition, the combination of ISP supplementation and RT had significantly increased type II muscle percentage and cross-sectional area (p < 0.05). Conclusion: Although ISP or RT alone improved muscle mass and performance, the combination of ISP with RT showed greater beneficial effects in aging mice. Our findings suggest that regular exercise along with protein supplementation could be an effective strategy to improve overall health and physical fitness among the elderly.

Effects of 8-week oral splint usage on body flexibility and muscle strength-endurance performance in Pilates practitioners

PurposeWe investigated the acute and chronic effects of oral splint on muscle strength-endurance performance and body flexibility.MethodsTwelve Pilates practitioners (age 49.5 ± 5.8 years; mass 58.6 ± 6.5 kg) were evaluated with (OS) and without (CTRL) oral splint. Before (PRE) and after (POST) 8 weeks of oral splint usage during Pilates activity, muscle strength-endurance and body flexibility were evaluated through a frontal plank exercise and a Toe-touch test in OS and CTRL. Before each test, the highest electrical activation (EMG) of masseter and temporal muscles during maximal occlusion was determined. During frontal plank, the time-to-exhaustion, the maximum voluntary activation of masticatory muscles and the time of muscles activation have been determined.ResultsNo OS vs CTRL and PRE vs POST differences were found in the maximum voluntary activation of temporal and masseter muscles. The time-to-exhaustion in OS was longer than CTRL in both PRE (P = 0.049) and POST sessions (P = 0.043). Time of masticatory muscles activation during plank was moderately greater in OS at PRE (P = 0.020) and POST (P = 0.022), while no difference between PRE and POST emerged in both conditions. Higher muscular activation was found in OS than CTRL at PRE (P = 0.031) and POST (P = 0.031), whereas no difference between PRE and POST appeared. No effect on flexibility emerged neither acutely nor chronically.ConclusionAcute and chronic oral splint usage improved strength-endurance performance but not body flexibility. These findings suggest biomechanical and neural mechanisms influencing the muscle length and the concurrent activation potentiation, but not muscle tone and stiffness.

Caffeine ingestion attenuates diurnal variation of lower-body ballistic performance in resistance-trained women

ABSTRACT The present study investigates the effect of an acute intake of caffeine on the diurnal variation of neuromuscular performance in resistance-trained women. A total of 15 resistance-trained women participated in the current triple-blind, placebo-controlled, crossover experimental study. We assessed neuromuscular performance (i.e. ballistic (countermovement jump [CMJ] height and bench press throw [BPT] peak velocity), maximal strength (squat and bench press [BP] one-repetition maximum [1RM]), and strength-endurance [average velocity of the set during squat and number of repetitions-to-failure in BP]) four times at within 7 days. The participants ingested an acute dose of caffeine (3 mg/kg) or a placebo at 9–11 am and/or 17–19 pm. CMJ height (P = .016) and BP peak velocity (P = .012) were higher in the afternoon than in the morning. Compared to placebo, caffeine intake increased CMJ height by 3.1% in the morning and 1.6% in the afternoon (P = .035), but it had no effect on BPT peak velocity (P = .381). Maximal strength and strength-endurance performances were not affected by the time-of-day or caffeine intake (all P > .3). No significant interaction (time-of-day x substance) was observed in any of the above-mentioned outcomes (all P > .1). In conclusion, an acute dose of caffeine in the morning was effective to restore CMJ performance to levels found in the afternoon, while this effect was not observed neither in BPTpeak velocity nor in lower- and upper-body maximal strength and strength-endurance performance. Moreover, lower- and upper-body ballistic performance were greater in the afternoon than in the morning in resistance-trained women, while the acute intake of caffeine was only effective to increase CMJ height. Highlights Ballistic performance is probably higher in the afternoon than in the morning in resistance-trained women. An acute intake of caffeine is effective to increase countermovement jump performance. The ingestion of an acute dose of caffeine in the morning restored countermovement jump performance to levels found in the afternoon.

The effect of physical abilities material, Vo2max index, and achievement of 400-meter freestyle youth

The aim of the research is to prepare special skill physical exercises using resistances such as swimming pockets and drag pockets that are the central axis of the body, with the aim of developing the special physical abilities of 400 m swimmers (such as special speed, special endurance, strength endurance and endurance performance within the competition time). The talent for swimming in Baghdad, and the special tests were determined (swimming 25 m from the start, swimming 50 m from stability, swimming 450 m, the RAST test (fatigue index) and the indirect Vo2max index test), and pre-tests were conducted, and resistance exercises were applied for a period of time. (8) weeks, at a rate of two units per week, after which the post-tests were conducted, and the results of the research showed clear superiority of the experimental group members in all special physical abilities and the development of fatigue index and VO2 max capacity index.

Concurrent Training and the Acute Interference Effect on Strength: Reviewing the Relevant Variables

ABSTRACT This review analyzes relevant variables involved in acute interference effects of concurrent training (CT) sessions of aerobic exercise followed by strength exercises. The aerobic exercise intensity, mode, volume, duration of recovery interval between exercises, muscle groups involved, and utilization of ergogenic aids are the variables identified in this review. High-intensity interval aerobic exercises result in more pronounced negative effects on strength-endurance exercise but not in maximal strength. Cycling results in more negative effects on strength-endurance performance exercise than running. A 4-hour to 8-hour recovery interval seems to be enough to avoid interference on strength-endurance performance. Reduction in strength-endurance performance is located in muscle groups involved in both exercises. Low aerobic exercise volume (3 km) with ∼18 minutes of duration does not diminish strength endurance, whereas higher volumes (5 and 7 km) with ∼30 and ∼42 minutes of duration, respectively, generate impairments. Caffeine, carbohydrate, and beta-alanine are not able to revert the deleterious effect on strength-endurance performance, whereas creatine and capsaicin analog supplementation are. Thus, these variables must be taken into consideration to prescribe and organize a CT session. This information may help coaches to organize exercise sessions that minimize or avoid the impairment in strength performance after aerobic exercises.

Ballistic, maximal strength and strength-endurance performance of male handball players: Are they affected by the evaluator's sex?

This study aimed to elucidate whether ballistic, maximal strength and strength-endurance performances are affected by the sex of the evaluator. Sixteen young male handball players attended two testing sessions that only differed in the sex of the evaluators (2 women vs. 2 men). The two sessions were performed in a counterbalanced order. Ballistic performance (countermovement jump height and throwing velocity), maximal strength performance (squat and bench press [BP] one-repetition maximum [1RM]), and strength-endurance performance (number of repetitions-to-failure in BP and average velocity of the set in the squat) were assessed in both sessions. BP 1RM was greater in the presence of women evaluators (p = 0.036, ES = 0.09), whereas no differences were observed for the remaining variables (p ≥ 0.254, ES ≤ 0.19). Low correlations (r median [range] = -0.074 [-0.693, 0.326]) were observed between the different performance tests for the percent differences between both testing sessions. The sex of the evaluators has minimal influence on a number of physical traits in young male handball players when they are tested in the presence of other members of the team, while the low correlations indicate that a higher performance in one test under the presence of women does not imply a higher performance under the presence of women in other performance tests.

Caffeine ingestion increases the upper-body intermittent dynamic strength endurance performance of combat sports athletes

ABSTRACT The aim of this study was to investigate the effects of caffeine ingestion on upper-body intermittent strength endurance performance of combat sports athletes. Using a double-blind and placebo-controlled crossover design, ten experienced judo and jiu-jitsu athletes performed an upper-body intermittent strength endurance protocol (four set of judogi dynamic strength endurance test, interspersed by 3-min recovery intervals) 60 min after ingesting either caffeine (5 mg·kg−1) or placebo. Compared with placebo condition, caffeine ingestion significantly increased the total number of repetitions (+ 7%, P = 0.04; d = 0.44) and the maximal isometric handgrip strength (+ 5%, P = 0.03, = 0.41). Rating of perceived exertion, heart rate and blood lactate concentration increased linearly throughout the test (P < 0.05), but without significant differences between caffeine and placebo conditions (P > 0.05). Caffeine ingestion improved the upper-body intermittent strength endurance performance and maximal isometric strength of combat sports athletes. This suggests that caffeine could help to maintain high levels of maximal handgrip and endurance strength in upper limbs, especially forearm muscles, which are responsible for maintaining the grip on the opponent’s judogi. Highlights Caffeine ingestion improved upper-body intermittent strength endurance of grappling athletes. Caffeine ingestion increased maximal isometric handgrip strength of grappling athletes. Heart rate, lactate concentration or rating of perceived exertion were not affected by caffeine ingestion. Our findings suggest that caffeine could help to maintain high levels of maximal handgrip and endurance strength in upper limbs, especially forearm muscles, which are responsible for maintaining the grip on the opponent's judogi.

Associations of Body Composition, Maximum Strength, Power Characteristics with Sprinting, Jumping, and Intermittent Endurance Performance in Male Intercollegiate Soccer Players.

The purpose of this study was to determine the relationships between body composition, strength, power characteristics, sprinting, jumping, and intermittent endurance performance in collegiate male players. Twenty-three players participated (19.7 ± 1.6 yrs; 71.8 ± 7.1 kg; 176.5 ± 5.1 cm). Measurements of interest in body composition included body fat percentage (BF%), lean body mass (LBM), and body mass (BM). Power characteristics were measured with an unloaded squat jump (SJ0) and loaded SJ at 20 kg (SJ20) and 40 kg (SJ40), and unloaded countermovement jump (CMJ0). Power assessments included peak power (PP) and PP allometrically scaled (PPa). Strength characteristics were assessed using isometric mid-thigh pull. Strength assessment included isometric peak force (IPF) and IPF allometrically scaled (IPFa). Performance measures included 10m and 20 m sprint time, CMJ0 jump-height, and Yo-Yo intermittent endurance test level 1 distance. Significant correlations ranging from moderate to very large were found for LBM and CMJ jump height (CM0 JH) (p = 0.01, r = 0.50); BF% and sprint times at 10 m (p = 0.03, r = 0.44) and 20 m (p = 0.02, r = 0.50). PP and PPa from SJ0 and CMJ0 were significantly correlated to 10m sprint time (p < 0.05, r = −0.45 to −0.53) and 20 m sprint time (p < 0.05, r = −0.40 to −0.49). Our findings agree with previous literature in that body composition and power characteristics are directly related to soccer-related performance.

The effects of different doses of caffeine on maximal strength and strength\u2010endurance in women habituated to caffeine

PurposeThe main goal of this study was to assess the acute effects of 3 and 6 mg of caffeine intake per kg of body mass (b.m.) on maximal strength and strength-endurance in women habituated to caffeine. MethodsTwenty-one healthy resistance-trained female students (23.0 ± 0.9 years, body mass: 59.0 ± 6.6 kg), with a daily caffeine intake of 5.8 ± 2.6 mg/kg/b.m. participated in a randomized, crossover, double-blind design. Each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 3 mg/kg/b.m. (CAF-3) and 6 mg/kg/b.m. (CAF-6) of caffeine. In each experimental session, the participants underwent a 1RM test and a strength-endurance test at 50 %1RM in the bench press exercise. Maximal load was measured in the 1RM test and the time under tension, number of preformed repetitions, power output and bar velocity were registered in the strength-endurance test.ResultsThe one-way ANOVA showed a main effect of caffeine on 1RM bench press performance (F = 14.74; p < 0.01). In comparison to the PLAC (40.48 ± 9.21 kg), CAF-3 (41.68 ± 8.98 kg; p = 0.01) and CAF-6 (42.98 ± 8.79 kg; p < 0.01) increased 1RM bench press test results. There was also a significant increase in 1RM for CAF-6 when compared to CAF-3 (p < 0.01). There was a main effect of caffeine on time under tension during the strength-endurance test (F = 13.09; p < 0.01). In comparison to the PLAC (53.52 ± 11.44 s), CAF-6 (61.76 ± 15.39 s; p < 0.01) significantly increased the time under tension during the maximal strength-endurance test. ConclusionAn acute dose of 3-to-6 mg/kg/b.m. of caffeine improves maximum strength. However, these doses of caffeine had minimal ergogenic effect on strength-endurance performance in women habituated to caffeine.

Acute impact of blood flow restriction on strength-endurance performance during the bench press exercise.

The main goal of the present study was to evaluate the acute effects of blood flow restriction (BFR) at 70% of full arterial occlusion pressure on strength-endurance performance during the bench press exercise. The study included 14 strength-trained male subjects (age = 25.6 ± 4.1 years; body mass = 81.7 ± 10.8 kg; bench press 1 repetition maximum (1RM) = 130.0 ± 22.1 kg), experienced in resistance training (3.9 ± 2.4 years). During the experimental sessions in a randomized crossover design, the subjects performed three sets of the bench press at 80% 1RM performed to failure with two different conditions: without BFR (CON); and with BFR (BFR). Friedman’s test showed significant differences between BFR and CON conditions for the number of repetitions performed (p < 0.001); for peak bar velocity (p < 0.001) and for mean bar velocity (p < 0.001). The pairwise comparisons showed a significant decrease for peak bar velocity and mean bar velocity in individual Set 1 for BFR when compared to CON conditions (p = 0.01 for both). The two-way repeated measures ANOVA showed a significant main effect for the time under tension (p = 0.02). A post-hoc comparisons for the main effect showed a significant increase in time under tension for BFR when compared to CON (p = 0.02). The results of the presented study indicate that BFR used during strength-endurance exercise generally does not decrease the level of endurance performance, while it causes a drop in bar velocity.

Placebo Effect of Caffeine on Maximal Strength and Strength Endurance in Healthy Recreationally Trained Women Habituated to Caffeine.

Background: By using deceptive experimental designs, several investigations have observed that trained individuals may increase their performance when told they were given caffeine, when in fact they received a placebo (i.e., the placebo effect of caffeine). However, most of these investigations on the placebo effect of caffeine used individuals with low caffeine consumption or did not report habitual caffeine consumption, especially in studies analyzing resistance-based exercise. Hence, it is unknown if habitual caffeine consumers benefit from the placebo effect of caffeine on exercise performance. Thus, the aim of the present study was to analyze the placebo effect of caffeine on maximal strength and strength-endurance performance during the bench press exercise (BP) in women with mild–moderate daily consumption of caffeine. Methods: Thirteen resistance-trained women (BP one-repetition maximum (1RM) = 40.0 ± 9.7 kg) habituated to caffeine (4.1 ± 1.7 mg/kg/day) completed a deceptive randomized experimental design with two experimental trials. On one occasion, participants were told that they would receive 6 mg/kg of caffeine but received a placebo (PLAC), and on other occasions, participants did not receive any substance and were told that this was a control situation (CONT). In each experimental trial, participants underwent a 1RM BP test and a strength-endurance test consisting of performing the maximal number of repetitions at 50% of their 1RM. Results: In comparison to CONT, PLAC did not enhance 1RM (40.0 ± 10.5 kg vs. 41.0 ± 9.5 kg, respectively; p = 0.10), nor did it enhance the number of repetitions (32.2 ± 5.1 vs. 31.8 ± 4.5; p = 0.66) or mean power (130 ± 34 vs. 121 ± 26; p = 0.08) in the strength-endurance test. Conclusion: Informing participants that they were given caffeine, when in fact they received a placebo, did not modify any performance variable measured in this investigation. Thus, the use of the placebo effect of caffeine seemed an ineffective strategy to enhance muscle strength and strength endurance during the BP exercise in women with mild–moderate consumption of caffeine.

The Effects of Regular Cold-Water Immersion Use on Training-Induced Changes in Strength and Endurance Performance: A Systematic Review with Meta-Analysis

Cold-water immersion (CWI) is one of the main recovery methods used in sports, and is commonly utilized as a means to expedite the recovery of performance during periods of exercise training. In recent decades, there have been indications that regular CWI use is potentially harmful to resistance training adaptations, and, conversely, potentially beneficial to endurance training adaptations. The current meta-analysis was conducted to assess the effects of the regular CWI use during exercise training on resistance (i.e., strength) and endurance (i.e., aerobic exercise) performance alterations. A computerized literature search was conducted, ending on November 25, 2019. The databases searched were MEDLINE, Cochrane Central Register of Controlled Trials, and SPORTDiscus. The selected studies investigated the effects of chronic CWI interventions associated with resistance and endurance training sessions on exercise performance improvements. The criteria for inclusion of studies were: (1) being a controlled investigation; (2) conducted with humans; (3) CWI performed at ≤ 15°C; (4) being associated with a regular training program; and (5) having performed baseline and post-training assessments. Eight articles were included before the review process. A harmful effect of CWI associated with resistance training was verified for one-repetition maximum, maximum isometric strength, and strength endurance performance (overall standardized mean difference [SMD] = -0.60; Confidence interval of 95% [CI95%] = -0.87, -0.33; p < 0.0001), as well as for Ballistic efforts performance (overall SMD = -0.61; CI95% = -1.11, -0.11; p = 0.02). On the other hand, selected studies verified no effect of CWI associated with endurance training on time-trial (mean power), maximal aerobic power in graded exercise test performance (overall SMD = -0.07; CI95% = -0.54, 0.53; p = 0.71), or time-trial performance (duration) (overall SMD = 0.00; CI95% = -0.58, 0.58; p = 1.00). The regular use of CWI associated with exercise programs has a deleterious effect on resistance training adaptations but does not appear to affect aerobic exercise performance. PROSPERO CRD42018098898.